The best guard dogs are the ones properly trained to change from playful and puppy-like to ferocious and snarling in just seconds. Russian YouTuber kamaz222 has gone viral showing off his German Shepherd’s training.

With just one word, he instructs his dog to growl and dangerously showcase his snarly teeth. With just another simple command, the dog instantly return to a docile mood.

In just a matter of days, the video has collected over half a million hits so far.